Extreme pressure lubricants



Patente Dec, 20, 1949 M'ED STATES PATENT QFFICE Standard Oil Develoration of Delaware pment Company, a corpo- No Drawing. ApplicationDecember 29, 1945, Serial No. 638.433

7 Claims. (Cl. 252-475) The present invention relates to lubricants generally, and, more particularly, to lubricants providing a lubricatinfilm capable of withstanding high loads or pressures without rupture ofthe lubricant film.

It has been established that straight mineral lubricating oils do notprovide lubricating films of sufficiently high film strength toadequately lubricate moving metal parts which contact each other underhigh pressures such as are encountered in certain types of bearings,engines, gears, etc., and for the purpose of improving as much aspossible upon the load-carrying characteristics of ordinary minerallubricating 011, many E. P. additives, oiliness agents, etc., are knownto the art and have been extensively used with considerable success.Among the many E. P, additives heretofore recommended, those hydrocarbonderivatives containin both active halogen and active sulfur have provedthemselves to be very effective in increasing the load-bearingcharacteristics of mineral lubricating oil. Even though thesesulfur-halogen compounds are exceedingly successful as E. P. additivesmany of them have one characteristic which detracts from theiracceptability. This characteristic is that these sulfur-halogencompounds tend to be somewhat unstable during storage, especially attemperatures above 100 F., liberating a hydro-halogen acid which iscorrosive to metal containers.

Such sulfur-halogen compounds are frequently too corrosive for use withcertain types of bearings. Attempts have been made to overcome thisexcessive corrosiveness of sulfur-halogen compounds by the use ofinhibitors but without much success. While the use of inhibitors issomewhat successful in delaying the appearance of evidence of thecorrosiveness of sulfur-halogen E. P. additives, they are oftenobjectionable for the reason that they react with the additive or itsdecomposition products to give insoluble precipitates. Such reactionboth detracts from the quality of the E. P. additive and destroys theinhibitor.

An object of the present invention is the production of a novel, lesscorrosive type of sulfurhalogen compound. Another object is animprovement in E. P. lubricants. These and other objects will beapparent to those skilled in the art upon reading the followingdescription.

The present invention is based upon the discovery that the reactionproduct of a chlorinated hydrocarbon containing active chlorine and analkali metal salt of alkyl or aryl dithiocarbamic acid, which may alsobe designated as alkyl or aryl-substituted alkali metaldithioaminoformate, is an oil-soluble compound having the property inoil solution of increasing the load-bearing characteristics of a minerallubricating oil, and is stable during storage and relativelynon-corrosive to metals. This reaction is illustrated by the followingequation:

XCSSMet+RHalx+XCSSRHalx-1+MetHal wherein X is a radical selected fromthe group consisting of (1) dialkyl amines or amines having two like ordifferent alkyl, cycloalkyl, aryl, etc, radicals, such as diamyl amine,(2) monoalkylaryl amines such as xylidine, and (3) piperidine; R. is ahydrocarbon residue derived from a petroleum mineral oil distillate suchas paraffin wax, kerosene and aromatic petroleum fractions having from 8to carbon atoms to the molecule; Met is an alkali metal such as sodium,patassium, lithium, etc.; Hal is one of the halogens such as chlorine,bromine or iodine, of which chlorine is preferred and m is a positivenumber of sufiicient magnitude that the weight per cent of halogen inthe compound RHalx will range between 5 and preferably 30-40%. The valueof a: will therefore normally range between 2 and 5. The reaction may becarried out in the presence of a ketone solvent such as methyl ethylketone or acetone, although any other organic solvent, except alcohol,which is capable of dissolving the carbamate, may be used, and at thereflux temperature of the particular solvent employed. After thereaction is complete, which generally requires from 1-3 hours, thereaction mixture is filtered to remove inorganic salts, after which thesolvent is recovered by distillation and the product is refiltered toremove any residual inorganic salts that may be present.

The halogenated hydrocarbon represented by R"Halx which may be ahalogenated paraffin wax, kerosene or aromatic petroleum fraction ismade by halogenating the hydrocarbon selected until on a weightpercentage basis the halogen content of the halogenated hydrocarbonranges from about 5% to as much as 50%. One example of a suitablehalogenated hydrocarbon is one made by chlorinatlng kerosene to achlorine content of about 40%, by passing chlorine through kerosene atatmospheric pressure and a temperature of about -200 F. for 3 hours. Thetime required to suiliciently chlorinate a petroleum mineral oildistillate under these conditions of temperature and pressure will rangefrom about 30 minutes to 5 hours. Within the range specified, thechlorine content of the chlorinated hydrocarbon may be varied toaccommodate any previously determined sulfur-chlorine requirements inthe final product.

The alkali metal salt of the hydrocarbon substituted dithiocarbamic acidis made by reacting a primary or secondary amine, carbon disulfide andalkali metal hydroxide according to the following equation:

In this formula the radicals R and R possess the same designations aswere ascribed to R and R in the preceding formula illustrating thereaction between the carbamate salt and the halogenated hydrocarbon.Where the hydrocarbon substitutent in the dithiocarbamic acid is of thepiperidine type, the above formula is slightly changed since R. and Rform a part of a closed ring. In this case, the formula may be repre-'sented more generically as XCSSNa which, upon condensation with thehalogenated hydrocarbon, becomes XCSSEster, wherein X is an amine group,a nitrogen atom being attached to two carbon atoms which may form partsof separate hydrocarbon radicals or may be a part of a single cyclichydrocarbon structure. The reaction is carried out by suspendingstoichiometricamounts of amine and caustic in a solvent such as methylethyl ketone, which suspension isthen cooled in an ice bath or otherequivalent cooling means, and carbon disulfide is then added slowly withagitation. Since the reaction is exothermic, the carbon disulfide mustbe added cautiously so as to maintain the reactants at a low temperatureand prevent undue volatilization of the carbon disulfide. In view of thefact that carbon disuh fide is a highly volatile liquid, some excess, upto about over that theoretically required, may be used Without anyharmful efiects, for the purpose of compensating for any carbondisulfide lost through volatilization.

The substituted dithiocarbamlc halogenated esters, containing from about2 to 10% of sulfur and to of chlorine, resulting from the re-. actionbetween the alkali metal salt of the sub stituted dithiocarbamic acidand the chlorinated hydrocarbon can then be blended in amounts rangingfrom 2 to 30% by weight, based on the total composition, preferablyabout 10%, in a mineral lubricating oil to yield an extreme pressurelubricant. In compounding such an extreme pressure lubricant, any of thenumerous types of low pour point lubricating oils may be used; it ispreferred, however, to use a Pennsylvania type oil having a viscosity inthe range of from about to about 150 seconds S. U. V. at 210 F. and acold test below 0 F. The following examples will serve to illustratespecific embodiments of the invention:

EXAMPLE 1 20 parts by weight sodium hydroxide 42.6 parts by weightpiperidine 43.2 parts by weight carbon disulfide 407 parts by weightchlorinated kerosene con taining 39.8% of chlorine dium piperidyldithioiormate in the solvent. The chlorinated kerosene and 250 cc.additional methyl ethyl ketone were placed in a separate reactorequipped with a reflux condenser; the heavy yellow suspension was thenadded to the chlorinated kerosene in methyl ethyl ketone and the wholerefluxed for 2 hours. The reaction mixture was then cooled and filteredto remove sodium chloride and the filtrate distilled under a reducedpressure of 37 mm. to remove the methyl ethyl ketone. The residue fromthe distillation was again filtered to take out any last traces ofsodium chloride. 435 parts by weight of a product containing 4.9% sulfurand 31.2% chlorine were obtained. A 10% blend of this product in amineral lubricating oil of 45 seconds vis. at 210 F. carried a fullshock load of 15 weights in the Almen test as compared with 3 weightscarried by the straight mineral oil. The reaction product in thisexample may be appropriately described as a piperidyl dithioformicchloro-alkyl ester where the ester-forming group is chlorinatedkerosene. As previously indicated, this group may be a halogenatedparaffin wax or a halogenated aromatic petroleum fraction instead ofkerosene if desired.

EXAMPLE 2 20 parts by weight sodium hydroxide e25 parts by weight carbondisulfide 7 8.7 parts by weight diamyl amine 407 parts by weightchlorinated kerosene con taining 39.8% of chlorine The carbon disulfidewas reacted with the caustic and amine in the same manner as describedin Example 1, resulting in a clear yellow solution which was thenrefluxed with the chlorinated kerosene for 2 hours and the productisolated. 485 parts by weight of a product containing 5.3% of sulfur and28.6% chlorine was obtained. A 10% blend of this product in minerallubricating oil carried a full shock load of 15 weights in the Almentest. The composition thus formed may be considered to be a diamyldithiocarbamio chloro-alky'l ester where the ester-forming group ischlorinated kerosene. Instead of chlorinated kerosene, as previouslyindicated, halogenated paraffin wax or halogenated aromatic petroleumfractions may be used. More specifically, a. chlorinated pentadecylhydrocarbon may be used in lieu of or as a part of the chlorinatedkerosene in which case the reaction product would comprise or consist ofdiamyl dithiocarbamic pentadecyl ester.

EXAMPLE 3 20 parts by weight sodium hydroxide 43.5 parts by weightcarbon disulfide 62.1 parts mixed xylidines 405 parts of chlorinatedkerosene containing 39.8% of chlorine The caustic, xylidines and carbondisulfide were reacted in the presence of methyl ethyl ketone asdescribed in Example 1, yielding a heavy yellow suspension which wasrefluxed with the chlorinated kerosene in methyl ethyl ketone. Afterremoval of the solvent and inorganic salts, 449 parts of a productcontaining 3.4% sulfur and 30.4% chlorine was obtained. A blend of 10%of this product in mineral lubricating oil (45 vis. at 210 F.) carried afull shock load of 15 weights in the Almen test. As in Examples 1 and 2above, other halogenated hydrocarbons may obviously be substituted forchlorinated kerosene.

To illustrate the improved corrosion characteristics of the compounds ofthe present invention,

8 10% blends of these products in a highly refined mineral lubricatingoil (15 seconds vis. at 210 F.) were made up and tested according to thefollowing procedure. 200 cc. of the blend and 2 cc. of Water werevigorously agitated for 3 minutes. A Timken cup and an Almen pin werethen placed in the lubricant and the lubricant stored in an oven at 120F. for 48 hours at which time the extent of corrosion was noted. Theresults of these tests are shown in the following table.

Table I Extent of Corrosion Lubricating Oil+l% Commercial ExtremeMarked.

Pressure Additive. Lubricating Oi.+l0% oi the product made in VerySlight. Example 1.

Llibl'iCafllng2 Oil+l0% oi the product made in Slight Stain.

xampe Lubricating Oil+l0% of the product made in Do.

Example 3.

Commercial extreme pressure additive containing sulfur and chlorine, butno nitrogen.

What is claimed is:

1. An extreme pressure lubricant comprising a highly refined minerallubricating oil and 2 to 30% by weight, based on the total compositionof piperidyl dithioformic chloralkyl ester, where the ester-forminggroup is a chlorinated kerosene containing 5 to 50% by weight ofchlorine.

2. An extreme pressure lubricant comprising a highly refined minerallubricating oil and by weight, based on the total composition ofpiperidyl dithioformic chloralkyl ester, where the ester-forming groupis a chlorinated kerosene containing 5 to 50% by weight of chlorine.

3. An extreme pressure lubricant comprising a highly refined minerallubricating oil and 2 to 30% by weight, based on the total compositionof diamyl dithiocarbamic chloralkyl ester where the chloralkylester-forming group is chlorinated kerosene containing 5 to 50% byweight of chlorine.

4. An extreme pressure lubricant comprising a highly refined minerallubricating oil and 10% by weight, based on the total composition ofdiamyl dithiocarbamic chloralkyl ester where the chloralkylester-forming group is chlorinated kerosene containing 5 to by weight ofchicrme.

5. An extreme pressure lubricant comprising a highly refined minerallubricating oil and 2 to 30% by weight, based on the total compositionof xylyl dithiocarbamic chloralkyl ester, where the ester-forming groupis chlorinated kerosene containing 5 to 50% by weight'of chlorine.

6. An extreme pressure lubricant comprising a highly refined minerallubricating oil and 10% by weight, based on the total composition ofxylyl dithiocarbamic chloralkyl ester, where the esterforming group ischlorinated kerosene containing 5 to 50% by weightof chlorine.

7. An extreme pressure lubricant composition comprising a majorproportion of highly refined mineral lubricating oil and 2 to 30% byweight, based on the total composition, of the reaction product of analkali metal salt of a hydrocarbon substituted dithiocarbamic acid witha chlorinated hydrocarbon, said reaction product having the formulaXCSSEster where X is a radical selected from the group consisting ofdialkyl amines, monoalkylaryl amines, and the piperidine radical, theester- Iorming group being a chlorinated petroleum hydrocarbon radicalof 8 to 30 carbon atoms containing at least 5% and not more than 50% by

